1. Field of the Invention
The present invention relates to an ink jet print head and a manufacturing method thereof.
2. Description of the Related Art
Generally, an ink jet print head comprises a print element substrate and a support substrate. The print element substrate has ejection energy generation means, such as electrothermal transducers, ink ejection openings (or nozzles) and an ink introducing port. The support substrate is formed with an ink supply port.
The print element substrate and the support substrate are positioned and bonded together by an adhesive, which hardens by ultraviolet light and heat (hereinafter referred to simply as an adhesive), so that the ink supply port communicates with the ink introducing port. The adhesive used has a coupling agent, such as silane coupling agent, added thereto to enhance an intimate contact between the support substrate and the print element substrate.
If the coupling agent is not added to the boding agent, a high level of intimate contact cannot be obtained between the support substrate and the print element substrate during the hardening of the adhesive. Therefore, after the adhesive hardens, a part of the adhesive may flake off with elapse of time, causing problems, such as ink leaking out to an outer circumference of the print element substrate.
Further, if the adhesive that is hardened by ultraviolet light and heat is not used and a thermosetting adhesive that is hardened only by heat is used, the print element substrate must be held immovable in its place with high accuracy until the adhesive begins to exhibit enough adhesive force to fix the print element substrate in its position. This deteriorates a workability in a production process and therefore a mass producing performance.
For these reasons, it is effective to use the adhesive that hardens by ultraviolet light and heat. That is, the adhesive is first hardened in a short time by ultraviolet light to temporarily fix the position of the print element substrate with high accuracy. Then, those portions of adhesive that the ultraviolet light cannot reach is hardened by heat.
Since a part of such an ultraviolet light/heat setting adhesive hardens by ultraviolet light in a short time, the function of the coupling agent added to the adhesive may be lost in that part. That is, for the portion that has hardened in a short time by ultraviolet light, an improved intimate contact expected of the coupling agent cannot be realized. It is therefore desirable that the portion of the adhesive that is hardened by ultraviolet light be kept as small as possible on the condition that the print element substrate can be secured temporarily on the support substrate.
Because of its irregular reflections, the ultraviolet light that has struck the surface of the support substrate may reach those portions of adhesive that are not intended for direct exposure to the ultraviolet light, initiating their hardening. In such a case, those portions of adhesive that are supposed to harden by heat may also undesirably harden in a short time, deteriorating the reactivity of the coupling agent.